Acoustic energy sources of a wide range of frequencies and power have been copiously used during the past century for a myriad of applications ranging from communication, industrial surface cleaning and even jack-hammering (U.S. Pat. Nos. 3,969,984 and 4,166,507—Bouyoucus), underwater sonar echo ranging and acoustic scan imaging (U.S. Pat. No. 2,258,725—Rines), and medical diagnostic treatment and internal body examination (“sonogram”), and, with, particular reference to the eyes, pulverizing of lenses with cataracts for removal and replacement by an artificial generally plastic interocular lens (IOL), [U.S. Pat. No. 3,589,363—Banko and Kelman; Phaco-emulsification Surgery, Devine et al, Permagon Press 1991, pp. 1–5; U.S. Pat. No. 3,526,219—Balamith, and U.S. Pat. No. 3,857,387—Shock; Cavitron/Kelman Model 6500, etc.; Bausch & Lomb Storz Millenium Model; H. M. Clayman et al, J. Cataract Refract Surg., Vol. 12, March 1986, pp 158–161].
Ultrasonic cleaners and therapeutic and surgical ultrasound (phacoemulsification of cataractous lenses, lithotripay of kidney stones, sports injuries as to knees, shoulders, etc.) use relatively high power and relatively low ultrasound frequencies and generate heat in tissues.
The cataract is a clouding of the lens of the eye lying behind the eye iris and pupil, causing hazy or blurring vision as the lens focuses light onto the retina in back of the eye. In the normal lens, the water and protein therein serve to provide a clear lens. During aging (and for other causes, also), some proteins apparently clump together, clouding areas of the lens—forming commonly near the center of the lens (“nuclear”); but cataracts also form in the lens peripheral cortex region and spoke therefrom inwardly toward the center (“cortical”); and in other instances, as in the case of some diabetes, a so-called “subcapsular” cataract forms at the back of the lens.
The relatively high power or intensity of therapeutic lower-frequency ultrasound injected internally of the eye by the phacoemulsification instrument tip inserted into the small incision made in the front of the capsule holding the natural lens, phacoemulsifies the cataracted lens and, in effect, particularlizingly dissolves or emulsifies the same so that the particles or fragments may be gently vacuum-removed from the eye.
In connection with the phacoemulsification applications, ultra (or super-) sound impulses, generally in the relatively low ultrasonic frequency range of about 30 to 80 kHz at power levels of about 20 watts, more or less, are used, generating strokes of between about 1 to 4 mils (acceleration of up to the order of 125,000 grams), hammering, shattering and fragmenting microchips to emulsify into a suspension. A small incision is first made into the cornea next to the sclera into which a phacoemulsification ultrasound probe is introduced, ultrasonically to break up, rupture and fragment and emulsify the cloudy lens into tiny particles or pieces which can be removed through the top of the probe by the before-mentioned vacuuming of the fragments, so as then to permit subsequent introduction or implantation of an appropriate substitute artificial IOL.
Once it has been decided thus to surgically remove a cataracted lens, it is then necessary to measure the patient's specific internal eye axial and other dimensions as by echoing low power ultrasound pulses from the surfaces of the anterior cornea, anterior lens, posterior lens retina and scelera, and displaying the same, and making needed calculations for replacing the lens with an intraocular lens. Appropriately, such an ultrasound “measurement” of the eye is generally effected by probing the eyeball with an ultrasound probe for generally less than or of the order of a minute or so, and with relatively low power pulses (compared to those use for phacoemulsification) and of relatively high ultrasound frequency of about 10 MHz, more or less. Such “diagnostic” ultrasound pulses in the megahertz range and of relatively low power do not generate any substantial heat in tissue and have been safely used for such imaging measurements, not for therapeutic usages, and with total safety to the eye and its components. The type I3 SYSTEM A B Diagnostics ophthalmic ultrasound instrument of Innovation Imaging Inc. of Sacramento, Calif., for example, is widely used for such entirely safe eye measurement and imaging purposes. This enables determining, including imaging (approximately 25 cps repetition rate), the particular internal eye shape, lens position, and multi-dimensional and axial distances to the retina, etc., displaying the same on real-time pulse-echo displacement vs. time displays (A-type presentation) as the operator traverses with the probe, and/or converting the resulting echo digital signals into images, as with an oscillating transducer that enables also B-type presentation, as in the accompanying FIG. 1, where the lens (L) and retina (R) acoustic images of one of applicant's eyes is displayed. This is more fully described, for example, in the 1995 I3 SYSTEM—ABD manual of said Innovation Imaging Inc.
Underlying the present invention, however, is a serendipitous apparent discovery that by irradiating the eye by slowly scanning such a relatively low power relatively high frequency ultrasound probe beam over the closed eyeball lid and irradiating through a water-containing interfacing transparent cup over the open-lid eye, or contacting the open eye on a film of liquid de-sensitizing drops and/or of ultrasound coupling gel or the like, and for much longer periods than the minute or so of brief usual probing for obtaining eye-structure dimensional measurements, some of the pre-existing vision-inhibiting effects, as before described, appear to be rapidly and radically ameliorated.